Substance Player - Free program used to view .sbsar files, tweak exposed parameters, and export to texture maps.
Substance 3D Designer Steam Edition - Paid but powerful Material authoring tool.
Material Maker³ - Free and open-source, based on the Godot Engine.
Texture Lab - Free and open-source, written in TypeScript and hosted in an Electron app.
¹Since s&box uses OpenGL Normals, when downloading textures from either AmbientCG or PolyHaven use the normal with GL in the name and not DX
²Normals from CGBookcase will need to be inverted as they are DirectX Normals⁵.
⁵You can invert a normal by toggling Legacy Source1 Inverted Normals in the material editor InvertNormals.
³Before exporting a material from Material Maker you will need to convert the normal in the graph from the Material Maker’s internal format to OpenGL Normal convert node documentation
³To export from Material Maker, do 'File' > 'Export Material' > 'Blender' . From there you'll have .exr files whitch are your exported textures.
⁴Textures from Material Maker Site Will need to first be exported from Material Maker.